All E9x 3-Series have a center speaker mount on the top of the dash for a center speaker.

In 3-Series with the optional Individual Audio, Logic7 or Harman Kardon systems a center speaker, wiring and a grill trim will be installed from factory. In 3-Series with the standard HiFi or Stereo systems there will be no center speaker, wiring or grill trim installed.

This DIY will show the parts needed to either add or replace your OEM center speaker with an aftermarket coaxial and the labor process.

1. Remove center dash vent:

Using a trim tool, carefully pry the vent trim from the side opposite the windshield.

2. Remove speaker mount:

There will be 4 Torx T-20 screws holding the speaker mount to the dash. Remove speaker (3 Phillips screws) after removing the mount, it is easier.

Shown in photos: OEM coaxial center speaker in the Individual Audio system and OEM connector harness.

You either will have an OEM speaker and the connecting harness there or not depending on your OEM sound system (see above). But you will have the OEM mount trim regardless if there is an OEM speaker there or not.

3. Replacing the OEM center speaker with aftermarket:

In this photo (left to right) there are the front door OEM mid, the OEM center coaxial and a Vibe Slick 4 aftermarket coaxial for comparison. The Slick 4 was chosen for it audio specs, fitment in the OEM screw holes, quality of its build and materials and for its less than 50mm mounting depth.

This is the Slick 4 installed in the OEM mount; there are three OEM mounting screws in this trim. The Slick 4 built in basket has 4 detachable screw mounting tabs, one at each corner. Two tabs are cut and the Slick 4 is just pushed into the mount, secured by two OEM screws and one screw with a wide washer in the third OEM screw hole so that side of the Slick 4 is secured.

Nothing else is required to mount this particular speaker.

4. Install of new coaxial center speaker:

Using the included connectors of the Slick 4 and the OEM connector that matches the existing OEM socket in the dash, the Slick 4 is connected to the OEM center harness without cutting, tapping or splicing any OEM wires. Test the speaker response after plugging it into the OEM harness but before reinstalling the whole assembly.

The whole assembly then is installed in reverse order from the removal process.

This center speaker install/replacement is particularly effective when a DSP processor (MS-8, bit one.1, 3SIXTY.2) is installed so there will be an extra "ambience" in the frontstage.

Looking at the speaker grill on my car, it's solid in the middle section instead of the speaker screen in your pictures. I wonder if it means I don't have the center speaker. Would there be wires then? Without the wires, I think I'll give it up. :sigh

Looking at the speaker grill on my car, it's solid in the middle section instead of the speaker screen in your pictures. I wonder if it means I don't have the center speaker. Would there be wires then? Without the wires, I think I'll give it up. :sigh

My car is 2011 335i made in late Sept last year with standard audio.

There's no center speaker/wiring installed in your car as your system is not Harman Kardon, as stated in the DIY.

Have been looking for some easy and quick upgrades. Thought could have done this one.

The mount also serves as the vents bracket.

To have a center channel also means that you would need a processor that can provide the correct center channel information and a dedicated amplifier channel for it. So you would need more than just a center speaker, grill and the wires... easy, quick or cheap it won't be.

You could replace your OEM amp with a MS-8 processor and then you could install a center speaker there.

This is great info. I had been looking for a cheaper option for the center, but i was not sure what i could make to fit the three hole configuration. I have not been able to find this slick 4 in stock online however, i see a slick 40-v2, but it does not have the removeable screw tabs. Does the slick really sound good versus the IA speaker?

This is great info. I had been looking for a cheaper option for the center, but i was not sure what i could make to fit the three hole configuration. I have not been able to find this slick 4 in stock online however, i see a slick 40-v2, but it does not have the removeable screw tabs. Does the slick really sound good versus the IA speaker?

It sounds pretty good actually, although slightly lower in volume than the OEM. The Individual Audio speakers are very sensitive and matched to the OEM amp, so this was expected. However, they should sound great with an aftermarket amp/system by adjusting its level separately, something that I cannot do obviously with the OEM amp.

Ok, one more question. I haved been scared away from some coaxials because of the protruding tweeter. It looks like in the pictures above that both of these speakers have tweeters that extend past the cone. Is this kinda tight once you put the cover on? or is there lots of room for a tweeter that sticks out a ways?

One last question. Is the 50mm mounting depth mentioned on the slick 4 really a requirement for the center channel? I did not think mounting depth was a limit here.

In the case of my iDrive I can see that there is a piece of plastic (probably part of the ducts) close to the OEM center speaker magnet when installed if I remove the screen to see. So to avoid any possible issues a 50mm limit is conservative.

Ok, one more question. I haved been scared away from some coaxials because of the protruding tweeter. It looks like in the pictures above that both of these speakers have tweeters that extend past the cone. Is this kinda tight once you put the cover on? or is there lots of room for a tweeter that sticks out a ways?